How to Install Wall-Mounted Sensors for Optimal Energy Efficiency & Indoor Air Quality
Even the best quality measurement instruments for carbon dioxide, temperature, and humidity will provide inaccurate readings if they are not installed correctly. These installation tips for your wall mounted sensors from Forest Rock's IoT web shop will help you ensure that the people in the building that you control, will benefit from fresh air, thermal comfort, and healthy humidity levels. When sensors are installed correctly, HVAC systems can respond more precisely to changing conditions, thereby improving occupant wellbeing, while also reducing energy waste.
Why Proper Sensor Placement Matters
Poor sensor placement is one of the most common causes of inaccurate measurements. High quality sensors from our IoT web shop can provide accurate long-term measurements, but only if they are installed correctly. Everything from nearby heat sources to mounting height can affect readings, leading to poor energy efficiency and sub-optimal indoor air quality. Knowing the installation mistakes to avoid will help you provide your HVAC system with the best measurement data possible.
Where Should You Install Wall-Mounted Sensors?
Wall mounted sensors, also known as room or space sensors, play a crucial role in monitoring the conditions being experienced by the people occupying a building. As human comfort and safety are paramount for HVAC control decisions, proper sensor placement is essential to ensure accurate readings and optimal system performance.
Because you the BMS specialist are controlling airflow and quality for the benefit of humans in a space, wall mounted sensors should be positioned in a representative location where they experience the same conditions as people. It is important to pick a place with unrestricted airflow that has no nearby sources of thermal interference.
Measure What and Where You Want to Control
For CO2 measurements it is particularly important to consider what and where you want to control. CO2 measurements reflect a building's occupancy level so your HVAC system can provide optimal air quality. Because of this it is important to place the sensors roughly at breathing level, typically around one and a half meters from the ground, in order to accurately reflect the air quality people are experiencing. Placing your CO2 sensors any higher than this will give misleading readings as CO2 is heavier than air, so levels will be lower closer to the ceiling and higher closer to the ground.
A Real-World Example
Let's look at a real-world example. A convention centre thought their new HVAC control system was working accurately because the CO2 sensors they had installed in the rafters showed acceptable levels. But when the CO2 was measured at floor level the concentration was alarmingly high. Placing your sensors where people will be breathing ensures you do not under or over ventilate your space.
Another common installation mistake is installing sensors in direct sunlight or close to a heat source, such as a radiator or heating duct, or above a printer or photocopier. Basically, as with CO2, you want to make sure that you are measuring what people in the room are actually experiencing.
Ensure Your Sensors Are Oriented Correctly
Wall mounted sensors from our IoT web shop are designed to be mounted in a specific orientation. This is because both the sensors and the electronics are in the same housing, and even low-voltage electronics generate some heat. When installed correctly, this heat escapes through the top of the unit and fresh air naturally flows over the sensor, which is lower in the housing. If the sensor is mounted sideways or upside-down, heat cannot escape and the sensor will record a higher temperature reading and a lower humidity reading so check the sensor install sheets for orientation.
Heat is also an issue if you mount sensors above each other. Heat rising from the lower sensor can cause the one above to heat up, making readings inaccurate. For example, if you mount a temperature or humidity sensor above a carbon dioxide sensor you will get temperature readings that are too high or humidity readings that are too low. Make sure you either mount the sensors sufficiently far apart, or at least place the warmer sensor well above the other sensor.
Measurement Errors from External Factors
If you have sensors in a pressurised room, the pressure difference between the room and the wall cavity can be another source of error. This is because it can cause cold air, or air with low concentrations of CO2, to flow directly into the sensor unit via the wiring hole in the wall, which can significantly distort readings. To prevent this, you should seal the hole by either adding a backing plate to the sensor box or filling it with caulking or some other form of material to seal the hole.
Building materials can be another source of error, especially for CO2 sensors. For example, fresh concrete and certain types of plaster will absorb CO2 for some time, significantly lowering a room's CO2 readings. Another potential issue can be using CO2 sensors with automatic background calibration (ABC) logic. This type of sensor applies a correction value to the assumed CO2 level, which can result in an artificially low reading. Forest Rock sensors from our IoT web shop use superior calibration methods to avoid this issue.
Concrete and steel can also cause measurement errors due to their conductive properties. These materials are excellent conductors of heat, meaning they can act as a heat sink or heat source for any sensor that is mounted directly onto them. This makes temperature readings better represent the wall material rather than the air in the space being monitored. To counteract this, either mount the sensor on an interior wall or place an insulating material between the sensor and the wall.
Finally, if your space has a forced downward airflow, the measured temperature can be artificially raised as the heat cannot leave the sensor electronics effectively. You can counteract this effect by using a sensor that is designed for cleanrooms and other spaces with forced downward airflow. In these units the sensor is separated from the electronics to prevent heating while still ensuring sufficient contact with the environment.
Proper Mounting Techniques
When mounting your sensors from Forest Rock's IoT web shop, use either screws or Nano Tape if the installation surface allows, for a secure installation onto the wall surface. These methods ensure your sensors remain firmly attached to the wall and maintain accurate positioning over time. Avoid using Velcro or other temporary adhesives, as these are not secure enough and sensors are likely to get knocked off, compromising your measurements and potentially damaging the equipment.
11 Tips for Installing Wall-Mounted Sensors
Follow these essential guidelines when installing sensors from our IoT web shop to ensure optimal performance:
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Position sensors where they will experience the same conditions as room occupants.
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Ensure there is free-flowing air around the sensor.
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Make sure CO2 sensors are installed around one and a half meters from floor level.
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Do not position sensors near a heat source or in direct sunlight.
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Mount sensors with the correct orientation.
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Do not mount one sensor directly above another.
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Seal the wire feedthrough when installing sensors in pressurized rooms.
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Don't install sensors onto fresh concrete or plaster.
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Avoid sensors that use automatic background calibration (ABC).
10. Do not install sensors directly onto exterior walls made of concrete or steel.
11. For rooms with forced downward airflow, use a sensor designed for this purpose.
12. Mount sensors securely using screws or Strong Nano Tape on smooth clean surfaces.
Avoid double sided Velcro or temporary adhesives like No-Nails.
Conclusion
Correct sensor installation is not just a technical detail, it is a key factor in maintaining healthy, comfortable indoor environments for the people who use the buildings you control every day. By following these guidelines and using high-quality sensors from Forest Rock's IoT web shop, you'll ensure accurate measurements that enable your HVAC system to optimise energy efficiency while maintaining excellent indoor air quality. The investment in proper installation pays dividends through reduced energy costs, improved occupant comfort, and better building performance.